Process of forming battery plates



, facturing electrodes"for electric batteries" of Patented May 24, 1932 V V 1 UNITED STATES DAVID Purim; or PmLAnE-LrrrIArEn Nsflvmia rnocnss or romaine BATTERY PLATES 1v Drawing.

My invention relates to a process tor manuthe typein which a conducting support is coated withpreparations of lead which by subsequent treatment areconverted into ac tive material. Theo'bject of my invention is to provide an improved process whereby the lead compound can be a ,=pplied to theconducting support in such a way as to produce a coating of highly homogeneous character. dlstinguished by a desirable porosity." and applied in such a manner that the active mate-f rial formed from the coating wilibe more uniformly available for the chemical reactions which it undergoes during the ch ar 'ing and discharging of a battery;thus,"enab ing me to. construct an electrode with less active materialthan is now generally-employedp Another object or myinvention is to make available theuse'as acondncting support or supports which are thinner, that is lessmassive than the supports now generally used.

My invention depends upon my discovery that it is possible to electrically deposit eonaconducting support used :as thecathode of ane'lectrolytie cell finely divided preparations or leadsuspendedin the electrolyte andthat the deposit will orcan'be of ahi ghly desirabe consistency, porosity and 'c omposition especi-allywell adapted for conversioninto active material. V V

;3n practice "I have found that electrolytes well adapted for use with my process are those "formed of solutions of compounds of alkali metals electrvopos'it iv'e tojlead and which in a free state are reactive with water with generation of hydrogen and I have "also found that the radicalsjcombined with such metals shouldbe acids which arenot oxidizing or hydroxyls; 'The. compounds used as electroiytes must be of such a character as to form a stron'g'and conductive solu tion to carry the current passing through the cell. My best results havelbeen obtained with compounds of ammonium, magnesium, sodium and potash, Whenusingiammonium and {magnesium I prefer to employ them in the form of sulphates Hand when; using sodium 7 and. potassium I prefer to employ them as hydroxides, though I-have usedlsodinm thin- A pplication filed June 2,1929. semi me e; r f isulphate and sodium sulphate with (goodre V sults. I have used calcium sulphate with some succesaespecially where litharge-jiszth'e lead preparation WlllChiS to be deposited on the-cathode I have also used sodiu d calcium acetates withyhow'ever le'ss satis- 'lfa'ctory results and prefer notto use the acetates on account of the difiiculty-of elirninat mg the verydetrimental acetic acid from the I finishedplatei Outside of the class oafielectrolytes which I-v'have, 'mentioned-asfpcefen able'fl have found-that my process can be practiced with 'aneleotrolyte formed-with a solution otlead nitrate, especially; where litharge 1s the lead p'reparation'held in suspcniii sion in the electrolyte but as the nitric acid is anoxidlzing radical it will be amatter of a great, deal of trouble and expense toeliminate v i it from the plate, which wouldbeneces-sary to enable a satisfactory plate to be produced i i 111 thisQWay. l v f p y i The preparations ofleadwhichi,havesuc H fluence iofthe electric current will be Iarpid-ly deposited on thecathode. With some of the electrolytes mentioned it is obvioustha'tthere willbe some reaction between theelectrolyteand the lead preparation resulting inthe for- J nration of solublelsaltsof lead but in no case ,-will;there orneed there be anything .ap-

- v v is proaching'a complete solution of the sus-"cfi pended particles and the portionthercef diswith finely divided particles on the cathodes where the electrolyti -action ayvill convert itginto spongy lead; it will-alsobe obvious that the deposited particles of lead preparationwill by the electrolytic action be partially solved'in the electrolytefiwill be deposited o M V "convertedinto spongy-leads'o that the coat. ling on the cathode will in all cases consistin,

Lpartofthe lead preparation suspendedin'fi v .the electrolyte ail-din part oi the'spongy lead produced directly or indi-tectlyfirbinjtheeie particles. It will also-be obviousthat'itis practicable and it is also sometimes perhaps desirable:tozidissolveacertain-amountgof a m f soluble compound of lead inthe electrolyte for the purpose of increasing the conductiv- 'ity of the electrolyte and also of providing additional material to be deposited electrolytically from the solution.

While, as I have stated above, finely divided metallic leadis one of the preparations 7 of lead which I have found to be usablein my process, I have not found it to be an advisable lead preparation except in the cases where sodium or*potassium hydroxides are used as the electrolyte. V,

With regard to the particle sizes of the lead preparation suspended-in the; electrolyte and deposited on the cathode, I have found that particles which will pass a sieve of 300 mesh are generally satisfactory. It is obviously desirable to hold as much of the finely divided lead preparations in'suspension as is practicable and this can be 'inrcreased'by mixing colloidal agents, such for instance as'glycerine or silicates of soda with the electrolyteand also by'energetic agitax tion of the electrolyte, which agitation is also naturallyadvantageous as tending to disperse hydrogen promptly from the cathode.

It is of course possible to maintain a practically constant percentage ofsuspended lead :preparation in theelectrolyte by adding such' electrolytic action;

preparations to the electrolyte during the It is-entirely practical'by my process to "deposit from'the electrolyte not only the'fine ly divided particles ofv lead preparation suspended in it, but also to simultaneously de posit fine particles ofinactive material such as graphite, lamp black or properly treated wood flour; andthe use of materials of this kind has a practical value, especially in the preparation of negative plates.

Electrode battery pl tes preparedin 'acfcordance with my invention can be finished and formed by well known means. It is to be noted however that in mostcases the plates coated in theelectrolyticcell have their deposited lead material partly reduced, which i will tend to shorten the process offinishing and forming the negative plates. For this reason it is obviously advantageous in the preparation of positive plates to use the higher oxides of lead.'

'Ihave found that posited onthe cathode is much greater than where the'same' weight of material isdis' solved in the electrolyte and deposited as metallic sponge by the laws of electrolysis and that by charging the number'of suspended particles between anode and cathode with a given current I can regulatein the deposit the proportion ofcsolid particles, the amount of surface reduction of vparticles and the amount of spongy lead deposited from so- 'Ewample IQ-As anexample of the applicathe rate, at which the particles suspended in the electrolyte are detion of my processwhen redlead is used with sulphate ofammonia as electrolyte Without agitation I suspend in 100 cc. of a solution of ammonium sulphate 1.20 specific gravity,

100 grams of commercial fumed battery red lead containing 15 to 25% litharge or all that can be kept in suspension and I may add .1 to

2% of glycerine or .1 to .5.% silicate of soda to aid inthe suspension and help in cementing of plate ondrying. :If agitation is used '300 grams or more canbesuspended.

I use a current of from .1 to .5 ampere per square inch of exposed cathode surface. The red lead is not acted upon bythe sulphate of ammonium butthe mixedlitharage grams of finely divided lead and I have used a current of from .2 ampere to 1 ampere per square inch" of exposed cathode surface. v

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1'. In the manufacture of electricv battery electrodes in which va conducting support of the electrode to be formed is coated withlead compounds adapted to become active ma terial, the improved method of coating such supports which consists in charging an electrolytic cell with an electrolyte of such composition that it will under conditions of use react upon and bring into solution no more.

sov

current is stopped when I than a'portion'ofthe preparation of lead suspended therein, mixing with and suspending in said electrolyte fine particles-of preparations of lead adapted for use as an electrodecoating, inserting in the electrolyteso prepared as' the cathode electrode of the cell the conducting support and depositing thereon by electrical migratory action followed by partial'reduction' particles of lead preparations suspended in the electrolyte.

2. Inthe manufacture of electric battery electrodes in which a conducting support of the electrode to be formed is coatedwith' lead compounds adapted to become'active mate rial, the improved method of coatingsuch supports which consists in charging an e1ectrolytic cell with an electrolyte of such coms position that it willunder conditions of use react upon and'bring into solution a port-ion 'onlyof the preparation of lead suspended therein, mixing with and suspending in said electrolyte fine particles of preparations of' lead adapted for use as an electrode coating,

inserting in the electrolyte so prepared as the cathode electrode of the cell the conducting support and depositing thereon byelectrical migratory action followed by partial reduction particles of lead preparations suspended in the electrolyte and simultaneously electrolytically depositing lead from the leadsalts dissolved in the electrolyte.

3. The method of claim 1 in which the electrolyte consists of an aqueous solution of a compound of an alkali metal which in its.

metallic state reacts with water with evolution of hydrogen and which is electropositive to lead. V

4. The method of claim 1 as carried out with an electrolyte consisting of a solution of a metallic compound in which the radical is non-oxidizing in character.

gather with the lead 5. The method of claim 1 as carried out with finely divided inactive material also suspended in the electrolyte and deposited to preparation on the conducting support.

GJThe method of claim las carried out with agitation of the electrolyte.

DAVID PEPPER. 

